Create Walls: Every base has a ramp (or at least a choke point) that leads down from your base to the rest of the map. You can use two supply depots and a barracks to wall that area off and ensure that Zerg players can't destroy you with the dreaded Zerg Rush (ditto for Protoss Zealot rushes.) With supply depots in the way, the Zerglings will have to try to chew their way through while one or two marines slowly pick them off. If the Zerglings seem like they might get through, no problem, just bring a few SCVs over to repair the wall. Later in the game you can stall the enemy army by building a wall of supply depots at your expansions. These can be lowered to allow your army to pass, or raised to block the enemy.

Complement Marines and Marauders with Medivacs: The best tool a Terran player has in their arsenal is the Medivac. They both heal units and also provide a great transport option which you can use to drop your troops inside your enemy's mineral line. More importantly, they can be combined with the Stimpack ability to create an incredibly powerful force. Marines, Marauders, and Medivacs (called an MMM build) are the most popular Terran composition. Stim juices them up to do huge damage, while the Medivacs heal the damage they take.

Stutter Step Your Marines: If you let your marines stand still while shooting Zealots or Zerglings then they'll get eaten up quickly. You can extend their life by shooting, then quickly moving back a few steps, then shooting again (repeat forever.) Marines have a brief pause between their shots that you can use to put some distance between you and your opponent (without losing any of your damage output.). After targeting an enemy unit, right click to make your marine(s) run away. Then press "S" to make them stop. They'll automatically target the enemy unit that is in range. Run, stop, shoot. Run, stop, shoot. Master this maneuver and your marines and Marauders will be much more dangerous.

Check back tomorrow for tips on playing the Protoss, as well as some Heart of the Swarm-specific strategies.